The Chancellor is expected to unveil “new schemes to get credit flowing” on March 20, after the Bank left both interest rates and quantitative easing (QE) unchanged this month. Measures targeted at small businesses are most likely, said economists.

The Prime Minister fuelled the speculation by hinting at a new round of “monetary activism” in his speech yesterday, saying: “The Bank of England must support the recovery without putting financial stability at risk.”

Any new policy tools would be expected to be in place in time for the arrival of Mark Carney, the Bank’s incoming Governor, on July 1. They would probably be accompanied by change in the Bank’s 2pc inflation targeting remit, economists said.

The Bank’s decision to hold interest rates at 0.5pc marked the fourth year that they have been at a record low. Markets expect rates to remain at 0.5pc until half way through 2015. Last month, Sir Mervyn was one of three MPC members who voted to increase QE by £25bn to £400bn. If he stuck to his vote yesterday, it would have been the first time the MPC had over-ruled him for two months running in his ten years as Governor.

Treasury officials are looking at proposals to adapt the Bank’s mandate to give a greater priority to growth. The introduction of more flexibility in the target, as proposed by Mr Carney, is considered most probable, though the Treasury declined to comment.

A new set of tools would be welcomed by several members of the Bank’s Monetary Policy Committee (MPC), who have expressed concerns about QE’s continued effectiveness.

They are thought to be increasingly looking to the Funding for Lending (FLS) cheap credit scheme to drive growth. But, earlier this week, the Governor Sir Mervyn King branded its performance to date “disappointing”, as there has been little evidence that small businesses are being offered better borrowing terms.

Last month, the Bank discussed extending the FLS to “non-bank lenders”. Separately, Paul Tucker, the deputy governor, has said “the authorities and the Bank could play a role” in improving access to working capital finance for small and medium sized companies. In both cases, the decision would have to be taken by the Chancellor.

Simon Wells, UK economist at HSBC, said he expected the Chancellor to use the Budget “to announce a review of the monetary framework and possibly new schemes to get credit flowing”. He added that lack of clarity over its possible new policy tools may have persuaded the MPC to leave QE unchanged this month. He described the pressures on the Bank as “framework uncertainty”, which had left the MPC “in limbo”.

Joost Beaumont, UK economist at ABN Amro, said: “[The Bank] could extend the FLS in order to more directly support credit flows to small and medium-sized companies. It will probably work closely together with the Government to develop a new lending scheme, which Chancellor Osborne might announce at his Budget.”

Stoking speculation was the date of the Budget, on March 20, which coincides with the publication of the minutes to the MPC meeting, which will reveal the issues that were debated and how the vote was split.

Separate research by advisory firm CEB found that confidence is returning to Europe. Almost two-thirds – 60pc – of European executives are expecting sales growth this year, up from 45pc at the end of 2012, and business confidence across Europe is at its highest level in a year.

“The key factors behind the rise in confidence include signs of re-emerging growth in Asian markets, the resolution of the 'fiscal cliff’ deadlock in the US, as well as suggestions that the economic slowdown in the eurozone may have bottomed out,” CEB said in its survey of 2,000 executives across the world.